Hereditary motor and sensory neuropathy type VIC with optic atrophy (HMSN6C) is an autosomal recessive axonal sensorimotor peripheral neuropathy characterized by progressive distal muscle weakness and atrophy primarily affecting the lower limbs. Onset of neuropathy is in the first decade, manifest by difficulty walking and running and followed by similar involvement of the upper limbs and hands. The disorder is associated with distal sensory impairment, particularly of position and vibration sense, as well as areflexia; individuals usually have pes cavus, hammertoes, and atrophy of the intrinsic hand muscles. In addition, progressive optic atrophy and visual impairment occur during adulthood. Treatment with pyridoxal 5-prime phosphate supplementation (vitamin B6) may result in amelioration of symptoms and slow progression of the disease (summary by Chelban et al., 2019). For a general phenotypic description and a discussion of genetic heterogeneity of HMSN6, see HMSN6A (601152). [from OMIM]